It is known in the art relating to welding torches that welding torches generally include a flexible cable portion that delivers power, shielding gas, welding electrode, and sometimes cooling water to a tubular neck portion, which may be referred to as a gooseneck or swanneck. The neck portion delivers the power, shielding gas, welding electrode, and cooling water (if present) to a tip portion that is secured to an end of the neck portion. The tip portion may include a welding tip and a nozzle. Typically, a mounting arm that mounts the welding torch to a welding robot is attached to the welding torch at a point between the cable portion and the neck portion.
Accuracy is very important in robotic welding. The welding tip needs to be precisely and consistently located at a pre-determined three-dimensional point in space, measured from the welding robot's “face.” This three-dimensional location, commonly referred to as the “tool center point” or “TCP” of the welding torch, is critical to a successful robotic welding operation. The mounting arm and neck portion are solely responsible for locating and maintaining the position of the welding tip with respect to the welding robot's face, and therefore should be manufactured with a high degree of precision.
Conventionally, the mounting arm includes precision machined aluminum or steel parts which when assembled are easily held to tight tolerances. These mounting arms are associated with a high degree of repeatability. The size and thickness of the parts of the mounting arm also make the mounting arms sturdy, which helps the mounting arms maintain the TCP. Further, it is not difficult to make any number of mounting arms to the exact (or nearly exact) same dimensions.
On the other hand, the neck portion is conventionally made of brass, copper, and/or aluminum tubular parts that are precision machined, but these parts are put through imprecise operations such as brazing and bending during assembly. This makes finished neck portions vulnerable to inconsistencies in length, bend location, and overall dimensions. Additionally, the lack of precision in the bending and/or brazing operations makes repeatability difficult in the manufacturing of the neck portions. Therefore, it is difficult to manufacture even two neck portions that have exactly the same dimensions. Further, due to the relatively small diameter and inherent softness of the materials from which the neck portion is made, the neck portion is not truly rigid. All of these factors combine to have a detrimental effect on both locating and maintaining the TCP. Hence, the neck portion is a weak link in maintaining a precise TCP.
Furthermore, after any bending operation, the neck portion is typically placed into a precision machined locating fixture by an operator and the TCP is checked for accuracy. In almost all cases, the TCP is not at the correct location, and the neck portion must be manipulated by hand to attempt to bring it within the tolerances for the TCP. This checking and manipulating of the neck portion's TCP is time consuming and does not always result in a neck portion having an acceptable TCP.
Also, it is common during a welding process that movement of the robot will cause the neck portion to accidentally hit a fixed object such as the workpiece being welded or a clamp/fixture that is holding the workpiece in place. Such a collision is referred to as a neck “crash.” Often, a crash will result in bending of a conventional neck portion and subsequent misalignment of the TCP, requiring correction such as by the above-mentioned method.